The present invention generally relates to structural framework assemblies and more specifically to a frame corner assembly having particular, but not necessarily limited application to frames for large electrical enclosures such as switchboards and the like.
Enclosure frames for supporting substantial weight as encountered in large electrical switchboards are typically created from an assembly of elongated slender metal struts or posts converging from three directions to frame corners where they are joined in mutually perpendicular relationship. In order to provide a strong, rigid frame assembly, the posts are often welded together at the frame corners. While welding produces a satisfactory corner joint, the posts cannot be prepainted. Moreover, welding is relatively time consuming and expensive since jigs or fixtures to hold the posts in alignment and relatively skilled labor are required to assemble the frame.
An alternative and more popular assembly procedure is to construct the frame members or posts such that they can be joined by suitable fasteners, such as bolts, screws or rivets. U.S. Pat. Nos. 3,305,225, 3,353,854 and 3,357,727 disclose frame corner assemblies representative of this approach.
An object of the present invention is to provide an improved structural frame corner assembly.
Another object is to provide a frame corner assembly which accommodates plural frame members of uniform cross-sectional size and shape.
Yet another object is to provide a corner assembly of the above character which is capable of achieving a strong, rigid, corner joint in residual tension.
An additional object is to provide a corner assembly of the above character which is efficient in construction and convenient to assemble using relatively unskilled labor.
Other objects of the invention will in part be obvious and in part appear hereinafter.